Bouncing along a dirt road that winds through tropical rain forests, the Weyerhaeuser company's pickup truck suddenly emerges into a large, cleared area dotted with tiny pine trees.

Indonesians wielding machetes wade through the underbrush, backing at the weeds and vines that constantly threaten to return and choke off the young trees' growth.

Halfway around the world from its home base is Tacoma, Wash., Weyerhaeuser has been introducing Caribbean pine trees into the forest wilderness of Kalimantan, the former Borneo.

It is a controversial experiment that has cast the giant timber company as the environmental good guy in an emotional debate between conservationists and commercial interests. Virtually alone among the more than 400 foreign and domestic timber concessionaries in Kalimantan. Weyerhaeuser has been planting new trees, testing the soil and warning of the disastrous effects of uncontrolled timber operations.

Elementary as reforestation of timberlands may seem to American conservationists, it is a novel idea that has yet to gain wide acceptance in Indonesia and the rest of the under-developed world, where last great untapped wood reserves lie.

What happens here is, therefore, being closely watched by forestry experts, who warn that tropical rain forests in West Africa, Brazil's Amazon Basin and other parts of South-east Asia are among the most threatened resources on the planet.

Economic and political pressure here have been pushing in a direction that worries the environmentalists-toward accelerated cutting and massive exploitation of the 100 million acres of standing further on Kalimantan.

Government-planners in Jakarta view timber exports as a crucial source of royalties and revenues to finance other projects. Most of the generals and overseas Chinese financiers who have become partners in the foreign timber companies prefer to see profits distributed as dividends instead of being reinvested in reforestation programs, which will not yield income for years.

"Everything foresters talk about has been happening in Kalimantan in disastrous proportions," says Charles Lankester, senior forestry adviser for the United Nations Development Project. "It's a calamitous denuding of forests with a loss of soil fertilization and water. Companies like Weyerhaeuser are beginning to show the way in responsible forest management in large-scale operations.

The image of the ugly American multi-national is not a correct one. The real problem is fly-by-night operators who are heavily financed from outside and well equipped with bulldozers."

That an unprecedented timber boom is under way here is obvious. Flying over eastern Kalimantan, a traveler looks down on logging roads winding through the tropical canopy and rafts of logs floating down rivers on their way to waiting coasted freighters.

One mile downstream from the provincial capital of Samarinda, on the wide, powter-colored Mahakam River, hundreds of logs of meranti, a mahogany-like wood wait to be processed at the new plywood mill of Georgia Pacific, the American timber company.

The logging boom has lured many off-islanders to East Kalimantan. Newcomers from Sulawesi across the Makassar Strait have followed the new logging roads and burned down thousands of acres along them for their temporary farming operations.

Horror storkes abound about of of what goes on farther up the Mahakam River, in the wilderness where native Dayak and Kutai fishing people lived for centuries in a delicate balance with the tropical wildlife - with thousands of species of birds, rare orchids, orangutan and tarsier monkeys.

According to forestry experts and conservationists who have penetrated deep into the interior, logging already has inflicted extensive damage - some of its perhaps permanent. The main culprits appear to be Japanese, Korean, overseas Chinese and Indonesian timber companies operating with short-term concessions.

John Blower of the World Wildlife Federation in Bogor, Indonesia, says that although the timber companies harvest only 10 or 12 marketable species occupying as little as 30 percent of a typical acre, another 20 to 30 percent of the stand may be damaged when these choice trees are removed.

Travelers report seeing river banks stripped for miles and trees cut smaller than the legal minimum of a 20-inches diameter. Lumber rafts reportedly have been hijacked as they float downstream, and Weyerhaeuser officials say moonlight operators have stolen thousands of trees off the company's concession.

This hectic commercial activity is an outgrowth of far off events, particularly the housing boom in Japan and the onset of timber shortages and stricter environmental controls over forestry in North America and Europe.

In the 1960s, these trends caused the international timber companies-the "multipulps"-to start eyeing the 2.4 billion acres of hardwood forest in the world's rainy tropical belt. In Asia this wood, suitable for construction lumber, furniture, paneling and ships, stood close to the growing Japanese market and the plywood plants and sawmills of South Korea and Taiwan.

The rising cost of imported oil, food and other commodities was an incentive to poor countries to invite foreign capital and technology to exploit their untapped timber reserves to pay for these imports. Although Indonesia, for example, has 3 percent of the worlds proven oil reserves, its food import bill runs close to $1 billion.

This is about equal to its timber export revenues, which have shot to $1 billion from only $100 million in 1970.

Tropical hardwood also has become one of the fastest growing exports of other developing countries, providing about as much earnings as sugar, cotton and copper.

Until 1967, the Indonesian timber industry was under state control. There was little logging in Kalimantan. Most timber operations involved teak in Java. But in 1967, the new military government of President Suharto changed course and opened up the economy to foreign investment.

The structure of the timber industry that subsequently developed relied on foreign companies or local Chinese capital, but generals and senior military officers with ties to the government were brought in as "partners."

There was a scramble for control of Kalimantan's hardwoods-one of the largest reserves in Southeast Asia.Concessions were awarded amid widespread reports of political-favoritism and bribery.

Within a year, the government had approved nine projects with a capital value of $70 million and Weyerhaeuser and many others were conducting preliminary surveys. The Tacoma company obtained its first concession in 1969. Then, two years later, it bought out the larger, million-acre concession of American inventor and entrepreneur Leon B. DeLong for an estimated $34 million.

At that time, Weyerhaeuser also inherited DeLong's Indonesia partner, which had a 35 percent equity interest. The partner was the Indonesia company Tri Usaha Bhakti ("Three Great challenges"), an army-organized group that also has interests in rubber, cement, quinie and airlines.

The present director of Tri Usaha Bhakti is Gen. J. M. Joendes. Tri Usaha Bhakti is, in turn, owned by a foundation created by the Indonesian army to promote "social development" projects such as pensions for orphans and widows of army officials.

Given the need of local stockholders for dividends to finance "social development" obligations, Weyerhaeuser officials say the future of the company's replanting program is uncertain.

Company officials acknowledge that Weyerhaeuser game somewhat late to reforestation-and when it did so, it was under the economic pressure of policy changes ordered by the Indonesian government.

The 20-year concession agreement that Weyerhaeuser took over in 1971 called for the company to out a minimum of 1.2 million cubic meters a year. The company estimated it could keep to this target if it selectively logged the entire concession over 20 years. But in 1973 the government, concerned by the first reports of over-cutting in Kalimantan, ordered the pace of cutting slowed so it would take 35 years to work through the concession. The company figures this would reduce the annual harvest to 800,000 cubic meters.

Weyerhaeuser's solution was to continue cutting at the old rate, but to begin replanting 2,400 acres a year in new trees. According to local manager Bryce Webster, an acre of unmanaged dipterocarp, or tropical hardwood, forest adds about one cubic meter of wood a year. But trees in a managed plantation add about 10 times that. Webster figures that if pany's replanting program is uncer-of replanting it will compensate for the wood taken out of the forest in selective logging operations.

"We don't plan to convert the entire hardwood forest to pine," says Webster. "It might be only 10 per cent. But that would be adequate to more than replace the wood we've taking out and the rest could be left to regenerate itself naturally."

When Weyerhaeuser did decide to undertake a major tropical reforestation program, it had to turn to others for advice. This was so even though Weyerhaeuser had been logging in the Philippines and the Malaysian province of Sabah in north Borneo since the 1960s. To learn about plantations, officials visited Picop, a concession owned by the Soriano family in the Philippines.

Today, however, a visit to the company's plantation, reachable only by speedboat departing from the coastal port of Balik Papan, leaves no doubt that Weyerhaeuser has indeed poured money into reforestation, as well as into facilities and amenities for its 1,200 workers.

The company has built about 600 miles of all-weather rock-bedded roads, constructed a hospital served by two doctors, built homes for logging crews, which include Malaysians as well as Indonesians, and started malaria control.

Weyerhaeuser's Roy Voss, a soil expert, has organized what may be Kalimantan's first vegetable garden. It produces nearly half a ton a month of papaya, beans, peanuts, tomatoes, eggplant, watercress and turnips for 500 plantation workers. Voss says he believes the vegetables have eliminated beri-beri, a fairly common illness resulting from vitamin deficiency in the local diet.

At the company nursery, women workers transfer tiny pine trees into plastic bags for planting. Other workers spray the pine plantations against insects and keeping down the weeds.

But for all these hopeful signs, Weyerhaeuser has run into a complicated series of political, commerical, biological and social problems that have made the future uncertain.

Company officials acknowledge that its partners and some parts of the government in Jakarta are lukewarm to the program, although officials of the Ministry of Forestry say they are enthusiastic.

Finance Ministry officials, are stressing the need to accelerate the cutting and export of logs. For instance, starting in 1976, Weyerhaeuser was asked to increase its annual cut to 1.4 million cubic meters.

"In dealing with our Indonesian friends we sometimes find ourselves in the odd situation of arguing on behalf of Indonesia's long-term national interests," said one timber company official.

Georgia Pacific, whose local partner is the influential Chinese financier and friend of Suharto's, "Bob" Hassan, has been praised by Indonesian officials for investing profits in Kalimantan's most modern plywood mill. "They feel that wood processing plants, not reforestation, is a better use of money," said one local forester. Suharto attended the inauguration of the Georgia Pacific facility, but has not visited Weyerhaeuser's Camp Kenangan.

Although Weyerhaeuser officials say they are "bullish" about the future of managed plantations in the tropics, the results so far have been mixed. The soi of Kalimantan is extremely poor-acidic and low in calcium and nitrogen-and there have been problems with most of the species that Weyerhaeuser has experimented with.

"You ask why Borneo is empty and Java across the strait has one of the densest populations in the world. The reason is that over there you can make a living on a few acres, but here the soil is such that you could starve to death on 600 hectares," says Webster as he kicks the Kalimantan soil.

The company has abandoned efforts to make plantations of indigeneous eucalpytus and albizia, a mimosalike tree. Nitrogen deficiency caused problems with the former and monkeys and deer ate the albizia leaves and knocked over the young seedlings. It is largely because of these problems that Weyerhaeuser has given priority to Caribbean pine, a species native to Honduras half way around the world.

The pine also has had problems with weeds and with "foxtailing," a genetic deformity that causes trees to grow up without branches. Another problem is that pine grows only about half as fast as the native hardwoods, which may explain why nobody has vet followed Weyerhaeuser's lead.

Company officials also are concerned about the influx of "slash and burn" farmers into its logging areas. The bleak predication of one official is that it could lost half the concession to the itinerant farmers if the government does not control the situation.

Weyerhaeuser's relationship with the Indonesian government in many ways typifies the tensions between governments and multinational companies around the world. In the era of the OPEC oil cartel, of which Indonesia is a member governments want multinational companies, but on the governments' own terms.

Weyerhaeuser officials concede that its Kalimantan operations still are highly profitable-only slightly more than $1 million a year is being diverted to the replanting program. But they insist that the returns are justified in light of the uncertainty and risks involved.

The company originally had assurances of duty-free imports of raw materials and equipment and of a low export duty. But in 1976, the Indonesian government unexpectedly tripled royalties and doubled the export tax on logs, from 5 to 10 percent, as an incentive to timber companies to do more processing in Indonesia. It also levied a registration fee of 1 percent on imported logging vehicles.

To the extent that the additional taxes are channeled into rural development, health, malnutrition in Java, surtaxes on timber firms may be justified. However, diplomats in Jakarta say much of these funds will be directed to capital-intensive projects such a mining and mineral and petroleum extraction, whose benefits are not spread widely.

The uncertainty was further underlined recently when Weyerhauser lost out in its bid to obtain another large concession, Kayan River. It went instead to an Indonesian concession Sumbra Mas (the "gold mine). "We don't know what happened," said a company official. "We thought we had it.'

Weyerhauser officials say they still are hopeful of win wider acceptance for the Camp Kenangan experiment.

"We know more about the soils of Kalimantan than anyone in the world," says Norman E. Johnson, vice president for the Far Eastern region. "We're testing the ecology and the biology. This is no roadside, eyewash operation."

However, whether Weyerhaeuser continues or accelerates its reforestation program is likley to depend more on decisions made in Jakarta than in Tacoma. The company officials say they are unwillling to commit more money under present conditions.

In what could be read as an implied warning to Indonesia, the World Bank has noted that "the failure to adopt a controlled forestry policy is attributable to a lack of political will, seflecting, both a short-sighted view and a long-established primitive attitude toward forests."